The present invention relates generally to a shear mechanism for cutting successive portions from a column of molten glass, and more particularly to an improved mounting of a shear blade adjustment mechanism.
Commonly assigned U.S. Pat. No. 4,215,611 to Dahms discloses a commercially successful system for straight line shearing of molten glass, which severs gobs of molten glass between "upper" and "lower" horizontally reciprocating shear blades. This patent discloses at column 4, line 29-column 5, line 63, with reference to FIGS. 1, 3, and 5 of that patent, an intricate system for mounting one or more lower shear blade to a lower shear head which, in turn, is mounted to a carriage member. The lower shear head incorporates an indexing mechanism which permits the user to adjust the shear blade tension by turning a hand knob affixed to the end of an indexing rod which is journaled in a wall of the shear blade frame. This patent further discloses at column 8, line 56-column 9, line 7, the possibility of changing over between a single blade (single gob) to two or more blades in the shear mechanism. It is noted that to change to a different number of lower shear blades, the shear blade bracket is removed from the carriage by removing certain bolts, and a new bracket equipped with the desired number of shear blades, and each blade with its adjustment mechanism then attached to the carriage. It is further noted that the indexing rods must be removed or added and spaced as necessary.
In producing a commercial embodiment of the apparatus of U.S. Pat. No. 4,215,611, designed to accommodate triple gob shearing, the assignee of the present invention refined the shear blade adjustment mechanism described above by replacing the simple hand knob at the end of the indexing rod outside the shear frame with a miter gear which mated With a miter gear at the end of a transversely oriented shaft. This shaft was journaled in a plate of the shear frame, and the hand knob was placed at the other end of the shaft. By providing a more remote control arrangement, this permitted a more convenient adjustment of shear blade tension from below the shear, which in operation in a glass plant, is located at a height making such adjustment inconvenient.
A problem inherent in the '611 design, not overcome by the refinement described above, is the extraordinary inconvenience of changing the lower shear blade assembly between, for example, double gob and triple gob configurations. Such changeovers are often required, for example, on a seasonal basis, in accordance with seasonal demands for different types of glassware containers. In this changeover, as discussed above, it is necessary to relocate the outermost lower shear heads, and their tensioning adjustment mechanisms, inasmuch as in the single and triple gob configurations these are located further apart than in the double gob configuration. (In the double gob configuration of this commercial prior art system, as well as that of the present invention, the central lower shear blade head may be indexed to an out-of-the-way position which will not interfere with the shearing operation.) This necessitated removing the two outermost indexing rods from one aperture in the end plate and reinserting and attaching it in an adjacent aperture. Furthermore, the outermost lower shear blade heads had to be removed and reattached. The maintenance operator was unable to obtain adequate access for this operation while the shear mechanism was attached to the feeder bowl by a bracket which partially blocks access to the end plate. Such changeover operation therefore required taking down the shear mechanism, causing highly undesirable down time.
Accordingly, it is an object to the present invention to provide an improved straight line shearing apparatus of the type disclosed in U.S. Pat. No. 4,215,611, wherein a changeover of such apparatus between double gob and triple gob configurations (or like changeover) may be accomplished in a more convenient manner. A related object is to eliminate the need to remove the shear mechanism from its mounting to the feeder bowl in order to accomplish such a changeover.